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  • 1
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    PANGAEA
    In:  Supplement to: Zhang, B Z; Zhang, P X; Lowenstein, Tim K; Spencer, R J (1995): Time range of the great ice age of the last glacial stage and its related geological event of playa in the Qinghai-Xizang (Tibet) Plateau. (doi:cnki:ISSN:10017410.0.1995-03-000 not valid), Quaternary Sciences, 3, 192-201
    Publikationsdatum: 2023-05-02
    Beschreibung: Fluid inclusions of protogenous halite, which were collected from two boreholes in the Charhan Salt Lake in the north part of the Qinghai-Xizang Plateau, werea nalyzed for their hydrogen and oxygen isotopes and for their Na, Mg etc. ions.On these grounds, the evolution of lake environment in this region during the last 50 000 years are discussed in this paper. The emphasis is to discuss the time range of extremely arid and cold climate at the last Glacial stage and the geological event of playa associated with such a climate.The guanidine hydrochloride method was used for measurement of hydrogen and oxygen stable isotopes. The measurement of Na, Mg etc. ions were achieved by determination of crystallization temperature of hydrohalite under microscope and then by calculation of chemical compositions of inclusion fluid using a thermodynamic model.The results obtained show that protogenous halite in the Charhan Lake area was formed in three different environment conditions: (1) In fluid inclusions of halite formed in the early period (50 000-30 000 a B. P. ), dD averages -14.9 per mil, d(18)O averages 8.37 per mil, and Mg(2+)ranges from 0.42 to 1.59 mol/L. Their plotting points fall on the right top part of the evaporation line of the present Charhan Lake area, indicating that the Lake water at that time had a higher concentration of brine, and the climate was hot and dry. (2) In fluid inclusions of halite formed in the middle period (30 000-15 000 a B. P.), SD average -66.0 per mil, d(18)O averages 1.00 pr mil, and Mg(2+) 1 mol/L. Their plotting points fall on the left low part of the evaporation line, indicating that the lake water at that time had a concentration of brine lower than that in the early period, and the environment was cold and dry. (3) In fluid inclusions of halite formed in the late period (15 000-present), dD averages 30.8 per mil, d(18)O averages 5.85 per mil, and Mg(2+) M 1 mol/L. Their plotting fall on the evaporation line, indicating that the climate environment at that time was warm and dry, almost the same as the present.The temperature variation of the last 50 000 years in the Charhan Lake area was calculated using the conversion equation proposed by Lorious et al. The time range of the Great ice age of the Last Glacial Stage is about 21 000-15 000 a B.P., which basically coincides with the time of a worldwide low sea level. The temperature in that period was below 0°C and 6-7°C lower than now. Because of lower temperatures, water supply to the lake area decreased rapidly and the concentration of lake water increased sharply. Therefore the Mg(2+) concentration in inclusion fluid reaches or closes to 2mol/L and the Mg/Na ratio varies within a very wide range. These show that the Charhan Lake at that time entered its playa stage. The Charhan Salt Lake is a typical one in the north part of the Qinghai-Xizang Plateau. It can be supposed that the extremely arid and cold climate of the Great Ice Age made most lakes in the north part of the Qinghai-Xizang Plateau enter their playa stage. This event is of importance for formation of salt resources.
    Schlagwort(e): AGE; Age, comment; Age, maximum/old; Age, minimum/young; Interpretation from literature (PKDB); Latitude of event; Longitude of event; Paleoclimate Database of the Quaternary; PKDB; PKDB286426; Precipitation, relative difference; Temperature, air; Temperature, relative difference
    Materialart: Dataset
    Format: text/tab-separated-values, 10 data points
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 161-163 (July 1998), p. 307-310 
    ISSN: 1013-9826
    Quelle: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Thema: Maschinenbau
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 71 (2000), S. 281-284 
    ISSN: 1432-0630
    Schlagwort(e): PACS: 68.55.Ng; 79.70.+q; 81.15.Fg
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract. Polyimide-ablated film was deposited by using pulsed laser ablation of a polyimide target, and field-electron emission from the film was observed for the first time. The turn-on field of the polyimide-ablated film is 12 V/μm. The current density is 0.725 mA/cm2, and the emission sites density is on the order of 106/cm2 at the applied field of 24 V/μm. The field-electron emission measurements indicate that this kind of film could be a new cold cathode material. It is suggested that the graphite-like clusters contained in the film play an important role in the field-electron emission.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 44 (1993), S. 535-539 
    ISSN: 1432-1041
    Schlagwort(e): Apolipoproteins ; Hypercholesterolaemia ; Pravastatin ; lipids ; lipoproteins ; probucol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary The effect of co-administration of low doses of pravastatin to hypercholesterolaemic patients already receiving long-term probucol treatment (mean 500–1,000 mg/day for 350 days) were investigated. Pravastatin 5 mg/day (Group 1; 12m, 13f; mean age 59.1 y) or 10 mg/day (Group 2; 8m, 11f; mean age 60.8 y) was administered, and blood was taken after 0, 3, 6, and 12 months. Both groups showed a significant reduction in serum total cholesterol (TC), phospholipid (PL), low density lipoprotein-cholesterol (LDL-C), LDL-triglyceride (TG), LDL-PL, apolipoprotein (apo) B, and apo E after the combined therapy. These levels were reduced more in Group 2 than in Group 1 subjects. In Group 2, significant falls in serum TG and apo CII were also observed. The changes in TC, PL, LDL-C, apo B, apo CII and apo E were dependent upon the dose of pravastatin, as assessed by two-way analysis of variance. Serum high density lipoprotein (HDL)3-C, apo AI and apo AII were slightly but significantly increased in both groups after 12 months of combined therapy, but the increase was not sufficient to reverse the probucol-induced lowering of the HDL level. We conclude that combined therapy resulted in a significant reduction in atherogenic lipoproteins and apolipoproteins, and an increasing dose of pravastatin (5 mg to 10 mg daily) made the lipid lowering effect more prominent. The reduction in serum HDL-C due to long-term probucol administration was not reversed by the addition of pravastatin.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    ISSN: 1432-1041
    Schlagwort(e): Bezafibrate ; Hypercholesterolaemia ; Probucol ; apolipoproteins ; lipids ; lipoproteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract The effects of the administration of slow-release bezafibrate to hypercholesterolaemic patients who were already receiving long-term probucol treatment (mean 865 days, 500–1000 mg·day−1) were investigated. Bezafibrate was administered at either 200 mg·day−1 (13 males, 13 females, mean age 55.2 years) or 400 mg·day−1 (11 males, 14 females, mean age 57.2 years), and blood was taken at 0, 3, 6 and 12 months after the beginning of combination therapy. Overall, serum total cholesterol (TC), triglyceride (TG), very low density lipoprotein (VLDL)-TC, high-density lipoprotein (HDL)-TG, VLDL-TG, VLDL-phospholipid (PL), lipoprotein (a) [Lp(a)], apolipoprotein (apo) C-III, apo E levels and LCAT activity decreased significantly with this combination therapy, while HDL cholesterol (C), HDL3-C, HDL-PL, apo A-I and apo A-II levels significantly increased, as assessed by analysis of variance (ANOVA). Five patients (one receiving 200 mg·day−1, four receiving 400 mg·day−1 bezafibrate) showed drastic reductions in HDL-C (HDL-C levels were reduced by a mean of 46.2%, 59.3% and 61.6% at 3, 6 and 12 months, respectively) after beginning combination therapy. These HDL-C reductions were maintained for the 1 year of combination therapy, but then returned to pre-combination treatment levels 1 month after discontinuation of bezafibrate. Serum probucol concentrations and cholesteryl ester transfer protein (CETP) mass were assayed at 6 months, and the probucol concentration was higher in the HDL-deficient group (56.2 vs 26.5 μg/ml). In contrast, CETP mass was significantly lower in HDL-deficient patients than in non-HDL-deficient patients (2.08 vs 2.87 mg·l−1). When the patients in the non-HDL-deficient group were divided into two groups, receiving low (200 mg·day−1, n−25) and high (400 mg·day−1, n−21) doses of bezafibrate, the former group showed a significant increase in probucol-lowered HDL-C and apo A-I, although these levels did not return to pre-probucol treatment levels, while the latter group showed no changes in HDL. These data suggest that the addition of a low dose of bezafibrate to probucol tended to reverse probucol-induced HDL lowering, while 9.8% (5 of 51 patients) of the patients exhibited a severe HDL deficiency. Since it is unclear whether or not such an extreme HDL reduction is harmful, HDL deficiency should be carefully monitored with this combination therapy.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    s.l. ; Stafa-Zurich, Switzerland
    Advances in science and technology Vol. 56 (Sept. 2008), p. 297-302 
    ISSN: 1662-0356
    Quelle: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Thema: Allgemeine Naturwissenschaft , Technik allgemein
    Notizen: The results of an initial investigation into the monitoring of water absorption and chemicaldegradation in epoxy matrix composites using evanescent wave spectroscopy are presented. Whileconventional silica glasses have too low a refractive index and too short an IR transmission windowto be useful as unclad sensing elements in most resin systems, chalcogenide glasses offer suitablerefractive indices and infrared transmission windows. Arsenic selenide compositions with galliumor tellurium additions were initially investigated as they have been successfully demonstrated inother fibre sensing applications. However their glass transition point lies near or below the curingtemperature for many commercial epoxy resins and thus germanium-antimony-lead sulphide glasseswere also investigated as they display higher glass transition temperatures. The fibres wereembedded in a representative matrix resin by casting samples of epoxy resin around sections offibre. The end faces were prepared to allow an infrared beam to be passed along the fibre and thesamples were subjected to hygrothermal aging. Changes in the transmitted spectra were observed,and photoelasticity was used to monitor the occurrence of fibre fragmentation. Both the arsenicselenide based compositions and the germanium-antimony-lead sulphide compositions displayedminimal bonding with the epoxy resin, so a simple silane treatment was used to improve adhesion
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 24-25 (Sept. 2007), p. 223-227 
    ISSN: 1662-8985
    Quelle: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Thema: Maschinenbau
    Notizen: Based on the kinematic analysis of the double sided polishing process, the equation ofrelative velocity (the workpiece to the polishing plate) is established. According to the Preston’sequation, the function of stock removal uniformity is presented. By computer simulations of themachining process, the effects of rotating speed ratios (the carrier revolution speed to plate rotatingspeed, carrier rotating speed to plate speed) on the stock removal uniformity are discussed in thispaper. At last, some experiments have been done for validating the theoretical study of stockremoval uniformity. The results show that, the computer simulation can estimate and conduct theexperiment result in double-sided polishing process
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 170-172 (Oct. 1994), p. 555-560 
    ISSN: 1662-9752
    Quelle: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Thema: Maschinenbau
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 551-552 (July 2007), p. 627-632 
    ISSN: 1662-9752
    Quelle: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Thema: Maschinenbau
    Notizen: Dynamic grain growth in superplastic AA5083 deformed at constant strain rates andvarying strain rates has been studied. It has been found that the strain rate history has a significantinfluence on the grain growth behaviour. It is proposed that differences in mechanical behaviour ofAA5083 for the strain rate conditions examined can be attributed to differences in the grain growthbehaviour. The influence of dynamic grain growth on the superplastic behaviour of AA5083 isdiscussed
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Il nuovo cimento della Società Italiana di Fisica 16 (1994), S. 1917-1924 
    ISSN: 0392-6737
    Schlagwort(e): Flux pinning ; flux motion ; fluxon-defect interactions ; Conference proceedings
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Summary Measurements of fundamental and higher harmonics of a.c. susceptibility on polycrystalline high-T c superconductors were carried out using a new method, involving a 2-channel dynamic analyser, allowing 20 harmonics in phase and out of phase to be measured at the same time. The critical-state model, used for describing the higher-harmonics dependence on temperature at fixed d.c. and a.c. magnetic fields, did not explain the experimental results. A frequency analysis indeed suggested that an effect of the fluxon dynamics takes place. Simple considerations lead to the conclusion that really Thermally Activated Flux Flow (TAFF), Flux Creep (FC) and Flux Flow (FF) would have a big role in determining the higher harmonics of a.c. susceptibility. Measurements on low-T c superconductors showed the occurrence of the same effect.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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